AR Build Checklist: Lower & Upper Receiver Parts – 100% Complete

AR Build Checklist

June 12, 2023 / Comments (0)

AR Build

Building your AR (AR-15 or AR-10) can be an exciting and rewarding experience. It allows you to customize your firearm to your exact preferences and specifications.

However, to ensure a successful build, it's essential to have a comprehensive AR build checklist. This checklist will guide you through the process, ensuring you have all the necessary components and information.

Understanding AR Builds

Before diving into the checklist, let's briefly understand what an AR build entails.

An AR build involves assembling an AR rifle or pistol from individual components. It involves selecting and purchasing the necessary parts, tools, and accessories and putting them together to create a fully functional firearm.

Building an AR allows for customization, cost-effectiveness, and the satisfaction of creating a firearm tailored to your liking.

AR Build Checklist – Essential Component

To build your own AR-15, you will need the following parts:

Lower Receiver Parts

Stripped lower receiver:

This is the part that is considered the “firearm” by law, and it is the only part that requires a background check and an FFL transfer in most states. It is a metal frame that holds all the other lower legs together.

AR build checklist

Forged receivers are more robust and cheaper, but billet receivers have more aesthetic options. Polymer receivers are lighter and easier to work with but less durable and reliable.

Lower Parts Kit

This kit contains all the springs, pins, detents, and other hardware you need to assemble your lower receiver.

Some kits include a trigger and a pistol grip, while others do not. You can also buy individual parts to upgrade or replace some components.


This part fires the rifle when you pull it. It consists of a trigger shoe, a trigger bar, a hammer, a hammer spring, a disconnector, and a disconnector spring.

You can choose between different types of triggers, such as single-stage or two-stage or drop-in triggers that come pre-assembled in a housing.

The quality of your motivation affects your accuracy and comfort, so it is worth investing in a good one.

AR build checklist

Buffer system: This part absorbs the rifle's recoil and returns the bolt carrier group to its original position after each shot.

It consists of a buffer tube, a buffer, and a buffer spring. You can choose between different lengths of buffer tubes, such as carbine-length or rifle-length tubes.

You can also choose between different weights of buffers, such as standard or heavy buffers. The importance of your buffer affects your rifle's cycling speed and reliability.

Stock or Brace

This part attaches to the end of your buffer tube and provides a stable platform for your shoulder when shooting.

You can choose between stocks or braces, such as fixed or adjustable, or pistol braces for short-barreled rifles or pistols. The type of stock or brace affects your comfort and maneuverability.

Upper Receiver Parts

Stripped or Assembled Upper Receiver

This part holds all the other upper parts together. It is a metal frame with a rail for mounting optics or sights. You can choose between stripped or assembled upper receivers.

Stripped upper receivers are bare frames requiring you to install additional parts, such as a forward assist and a dust cover. Assembled upper receivers come with those parts already installed.

Forward Assist

This small button on the side of your upper receiver allows you to manually push the bolt carrier group into the battery if it fails to do so automatically. It is not essential, but some people like to have it for extra reliability.

Dust Cover

This small flap on the front of your upper receiver covers the ejection port when the rifle is not in use.

It prevents dust and debris from entering your chamber and causing malfunctions. It is not essential, but some people like it for extra protection.


This part propels the bullet out of the rifle. It consists of a metal tube with a rifling inside to stabilize the bullet.

Depending on your intended use and preference, you can choose between different lengths, profiles, materials, and finishes of barrels.

AR build checklist

The size of your barrel affects your velocity, accuracy, and maneuverability. The shape of your barrel affects your weight, heat dissipation, and durability.

The material and finish of your barrel affect your corrosion and wear resistance.

Muzzle Device

This part attaches to the end of your barrel and affects the direction and intensity of the gas and noise that come out of the rifle.

You can choose between different types of muzzle devices, such as flash hiders, muzzle brakes, or compensators.

Flash hiders reduce the visible flash from your muzzle, making you less conspicuous at night. Muzzle brakes reduce your rifle's recoil and muzzle rise, making you more accurate and faster.

Compensators reduce the horizontal movement of your muzzle, making you more consistent and stable.

Gas System

This part uses the gas from the fired cartridge to cycle the rifle's action. It consists of a gas tube and a gas block.

You can choose between different lengths of gas systems, such as carbine-length or rifle-length systems. The size of your gas system affects your cycling speed, reliability, and recoil.

You can also choose between different types of gas blocks, such as standard or adjustable ones.

Standard gas blocks allow a fixed amount of gas to flow through the system, while adjustable gas blocks allow you to fine-tune the amount of gas to optimize your performance.


This part covers your barrel and gas system and provides a platform for mounting accessories like lights, lasers, grips, or bipods.

You can choose between different types of handguards, such as drop-in or free-float handguards. Drop-in handguards are easy to install and remove, but they touch the barrel and affect its accuracy.

Free-float handguards are harder to install and remove but do not touch the barrel and improve its accuracy.

Bolt Carrier Group

This part extracts, ejects, feeds, and fires the cartridges in your rifle. It consists of a bolt carrier, a bolt, a firing pin, a cam pin, a retaining pin, and a gas key.

Depending on your preference and budget, you can choose between different materials and finishes of bolt carrier groups.

The material and finish of your bolt carrier group affect your corrosion resistance, wear resistance, and lubricity.

Charging Handle:

This part allows you to manually pull back the bolt carrier group to load or unload the rifle. A metal handle slides into a slot on top of your upper receiver.

You can choose between different types of charging handles, such as standard or ambidextrous charging handles.

Standard charging handles are designed for right-handed shooters only, while ambidextrous charging handles are designed for suitable- and left-handed shooters.

Tools to Build Your Own AR-15

To build your own AR-15, you will need the following tools:

AR build checklist - AGA

Why Build Your AR-15?

You should consider building your AR-15 instead of buying a complete one. Some of the benefits of building your AR-15 are:

  • You can choose the parts and specifications that suit your needs and preferences.
  • You can save money by buying only the needed parts and avoiding unnecessary features or accessories.
  • You can learn more about how the AR-15 works and how to maintain it properly.
  • You can have a sense of pride and accomplishment from creating something with your own hands.

Benefits of AR Build Checklist

An AR rifle build checklist can benefit firearm enthusiasts or professionals assembling or modifying AR rifles. Here are some advantages of using an AR rifle build checklist:

  1. Accuracy and Precision
  2. Safety Compliance
  3. Comprehensive Guidance
  4. Time and Cost Savings
  5. Knowledge and Skill Development

Building your AR can be fulfilling, allowing you to create a firearm tailored to your preferences. By following a comprehensive AR build checklist, you can ensure a successful build with the right components and attention to detail.

Remember to prioritize safety, functionality, and compliance with applicable laws. It's time to start your AR build journey and experience the satisfaction of creating a personalized firearm.

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